Your analogy doesn't hold up. Your example is clearly theft, and is a criminal matter. Violation of a sites terms is a civil one, and again is a legal grey area. Scraping the site doesn't delete the content from a server...but there is only one copy of the dog.
EDIT - I can't reply to your comment below, but FWIW I agree that scraping sites in this manner is unethical. I am merely describing the logic that most scrapers go through for self justification and legal protection.
The analogy was "doing something anyway because you might be told 'no'", not "my server behaves like a canine quadruped". Copyright infringement is also potentially criminal in the UK, it's not as simple as you suggest.
But whatever. It just saddens me that the internet is a constant "don't be a dick" battle with companies like the scraper guys.
EDIT - I can't reply to your comment below, but FWIW I agree that scraping sites in this manner is unethical. I am merely describing the logic that most scrapers go through for self justification and legal protection.